Means for retaining lower partial dentures in the mouth.



g m %%WW I. M. DONAHOE.

MEANS FOR RETAINING LOWER PARTIAL DENTURES IN THE MOUTH.

APPLICATION FILED FEB. 14. 1916.

1. 63 18% Patented. Apr. 9, 1918.

2 SHEETS-SHEET 1-.

WITNESSES.-

J..M. DONAHOE.

MEANS FOR RETAINING LOWER PARTIAL DENTU'RES IN THE MOUTH.

I APPLICATION FILED FEB. 14, I916. 192m 4 Patented Apr. 9, 1918.

2 SHEETS-SHEET 2.

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Jana MICHAEL DONAHQE, or surnn ion, Wisconsin.

MEANS FOR RETAINING Lownn ran'rrar. connrunns IN was mourn.

To a ZZ whom it may concern Be it known that 1, JOHN M. DONAHOE, a citizen of the United States, residingat Superior, in the county of Douglas and State of Wisconsin, haveinvented a new and useful Means for Retaining Lower Fartial Dentures in the Mouth, of which the following is a specification.

This invention has reference to means for retaining lower partial dentures in the mouthand its object is to provide a means whereby lower dentures are retained with the aid of one or more natural tooth roots without pressure thereupon when the denture settles because of shrinkage of the process.

In accordance with the present invention a natural tooth root is properly prepared and 'crownedpwith a cap rising above the gum, but with the root protected by the extensionof the cap just underneath the f-ree margin of the gum. Usually it is preferred to utilize at least two roots, although good results may be obtained where only one naturalroot is available. In either case there is fitted to the abutment formed by the capped tooth a shell simulating, an ordinary crown,- and so constructed as to telescope upon the permanent cap; Such shell-like crown is firmly connected to and anchored in the denture, so as to constitute a permanent part thereof. The shell telescopes over the abutment in close relation thereto so as to anchor the denture in the mouth; but is capable of easy removal and of moving lengthwise of the abutment, in

the event of shrinkage of the gums and process, wherefore the denture is always supported by the process and at no time is the abutment or abutments, where two or more are used, subjected to the stress or pressure of mastication. At the same time the shell carried by the denture telescopes closely on the abutment shell or cap, so that there is nothing to catch or retain food, wherefore the structure is highly sanitary. Furthermore, the dentures are at all times freely removable.- a

. The invention will be best understood from a-consideration of the following detailed description, taken in connection with v the accompanying drawings forming part of this specification, with the further understanding that while the drawings show a practical form of the invention. the latter is not confined to any strict conformity with Specification of Letters Patent.

Patented Apr. 9, 1918 Application filed February 14, 1916. Serial No. 78,249.

the showing of the drawings, but may be changed and modified so long as such changes and modifications come within the scope of the appended claim.

In the drawings v Figure 1 is an elevation of an outer telescoping crown-shell structure adapted to be included in a partial denture, and showing a form where twonatural roots are available.

.Fig. 2 is a rear elevation of the structure of Fig. 1. i

Fig. 3 is an inverted plan view of the structure of Fig. 1.

Fig. i isa more or less schematic view of a lower jaw showing two roots with abutment crowns or caps thereon: I r

Fig. 5 is a plan view of a lower jaw with a. complete 'dentureexcept for the presence of a crown-shell structure such as shown in Fig. 1 applied to the partial denture.

I Fig. 6 is a front elevation of the structure shown in F ig. 5.

Fig. 7 is an enlarged elevation of one of also represent a single crown shell where but one root is available. Fig. 8 is a section through an applied crown shell on a prepared root, the showing being much enlarged and the relation; of the parts somewhat exaggerated for clearness of illustration. I j

Fig. 9 is a section on the line 9-9 of Fig. 3, but showing the shell upright.

Fig. 10 is a plan View of apartial denture with the parts joined by a connecting bar. Fig. 11is a plan view of such a denture applied to a lower jaw more or less schematically shown. I V

Fig. 12 is a side view of the showing of Fig. 11. I

Fig. 13 is a plan view of the lowerjaw prepared for the denture of Fig. 10. I

Fig.1t is a section on the line hie-14 of Fig. 11.

It has been heretofore proposed in connection with partial dentures to utilize one It is a feature of the present invention that firm anchorage and ready removal are roots 2, and it may alsobe assumed that all the other natural teeth of the lower jaw are missing, as in Figs. 4, 5 and 6, or that the jaw contains other natural teeth 3, as 111 Figs. 11, 12 and 13'and associated figures.

These two examples may. be taken as representative. of any conditions where a partial denture for the lower jaw is to be supplied. The natural. tooth or teeth 2 are each supplied above the gums and slightly below their free margins with a permanent cap t cemented to the tooth or root after being properly prepared. The cap 4: should not project to the full natural d stance from the gums of the tooth to which 1t is secured.

Adapted to the cap 4 is a crown shell 5 arranged to telescope snugly yet freely on the cap a, without, however, at any time coming in contact with the outer or free end of the cap l. The crown shell 5 may simulate any exterior conformation of the natu ral shape of the tooth to which it is applied, so that when in the mouth the appearance is that of an ordinary gold crown. 7 Considering that the lower jaw contains two suitably spaced prepared natural roots, as indicated in the drawings, two similar spaced crown shells 5 are provided,and each shell has a reinforcement hat the cervical margin to prevent stretching on being applied to and taken from the caps 1 many times. The reinforcement 6 may be formed with ears 7 for properly holding the crown shells to the mold during the application of the rubber and the artificial teeth thereto. The shells 5 have projections 8 extendingv therefrom and constituting anchors to be embedded in the rubber or other material of which the denture is formed, and in the event of there being more than one root available, the shells 5 are connected by a junction bar 9. l/Vhere the capped roots are separated by natural teeth, as the teeth 3 of Figs. 11, 12 and 13, the junction bar 9 may be exposed, and be situated close behind the natural teeth, where it will neither interfere with mastication or be annoying to the user. Where the only natural teeth remaining in the lower jaw are those which are provided with'the crown caps 4, then the bar 9 is embedded in the rubber plate, as are also the anchors 8. This gives additional strength to the denture, especially where the caps are applied to spaced roots and the parts of the denture are separated by the crown shells 5, such arrangement being shown in Figs. 5 and 6. j I

In the several figures the artificial dentures are indicated at 10 for the one illustrated in Figs. 5 and 6, and at 11 for the one illustrated in Figs. 10, 11, 12 and 14.

"With such an arrangement the crown s iells snugly telescope on the caps of the appropriate roots, so that there is no space left for the lodgment of food or other matter, but this arrangement in no wise interferes with the ready removal of the denture for cleansing and other purposes. The arrange ment, therefore, is highly sanitary;

The process and the gums of the jaw naturally shrink in the course of time, and-were it not for the telescoping of the shells 5 upon thecaps the pressure of mastication would quickly be localized upon the prepared roots for the shrinking gums would soon fail to properly support the denture. Should such a condition occur the pressure by mastication being principally upon the prepared roots, the latter are liable to become sore and to decay, requiring frequent treatment and probable loss of the roots.

With the. present invention the pressure of mastication at no time is brought to bear upon the anchoring roots, for the gums fully support the denture even though the gums shrink considerably. In the case of such shrinkage which invariably takes place, the shells 5 merely telescope to a greater extent upon the caps or crowns 4:. The pressure of mastication will come upon the shells 5 the same as upon the other artificial teeth, but is transmittedto the body no soreness of the roots is produced, and 7 they being protected by the cap shells 4 above the gums remain indefinitely free from decay. Moreover, the roots are protected at all times by the shells 5 while serving to-adequately anchor the denture to the lower jaw against such displacement as frequently occurs in'lower jaw dentures as ordinarily constructed. Moreover, in the case of partial lower jaw dentures the invention provides a connecting means spanning the weak places in the denture, wherefore breakage of the partial dentures because of such weak places is wholly avoided. Furthermore, the bar connecting the crowns where more than one crown isen'r ployed is wholly embedded in the body of the denture, or is hidden from View, being located back of the gums, as in an arrangement like that illustrated in Fig. 11.

W hile the present'invention may be used place whether or not the crown of the tooth be all decayed or broken away, it is better if there be two teeth or roots in place one on either side of the lower jaw.

What is claimed is A partial denture for a lower jaw having one or more natural teeth or roots and each provided with a cap extending to a less ieight than a natural tooth, said partial denture having one or more crown shells in accordance with the number of natural roots available, with said shell or shells anchored in the denture in position to articulate with the teeth of the upper jaw, whether such teeth be natural or artificial, and arranged to telescope snugly yet freely upon the cap or caps of the appropriate root or roots in the lower jaw, the shell or shells being of greater height internally than the extent of telescoping of the shell or shells on to the cap or caps, whereby to avoid abutting engagement of the shell or shells with the corresponding cap or caps and completely protecting the natural root or roots from all pressure of the partial denture or exposure of the natural root or roots to the forces exerted during mastication, said partial denture being capable of free removal from and application to the lower jaw at any time by the wearer.

In testimony that I claim the foregoing as my own, I have hereto afiixed my signature in the presence of two witnesses.

JOHN MICHAEL DONAHOE.

Witnesses:

H. L. LLOYD, ADA MORTENSEN.

fioples 0! this patent may be obtained for five cents each, by addressing the Commissioner of Eatenta.

Washington, D. G." 

